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Selection of working fluid is one of the main criterions for designing of heat pipes thermal control systems (TCS) for space application. In this paper we will describe how we solved the task of development of the TCS with working fluid of high thermal physical properties. In 2004-2006 we developed the Engineering model of Deployable Radiator based on Loop Heat Pipe by CAST purchase order. It was developed for qualification tests. Ammonia application as LHP working fluid is stipulated by its high thermal physical properties. However Ammonia freezing temperature is of minus 77ºC. Such fact impedes Ammonia application when operation temperatures of LHP Radiator are lower than this value, for example, It takes several tens of hours to orbit a spacecraft and prepare it for work (at that moment the spacecraft is out of power supply) and the working fluid can be frozen in a condenser-radiator when the spacecraft being in the shadow over a long period of time.

Experimental investigation results of developed Axial Heat Pipes with Ω-shape grooves (“Re-Entrant” grooved geometry) are presented in this paper. Influence of working fluid mass and tilt angle on Axial Grooved Heat Pipes characteristics is also described in the paper. Experimental dependence of heat transfer capacity on operating temperature is compared with calculation results. This paper is dedicated to investigation of influence of heat input and heat output sources location on AGHP characteristics under on-ground conditions. Values of heat transfer coefficients in the zones of evaporation and condensation for 3 different AGHP samples are also presented in this paper as well as test results for burst pressure. AGHP qualification test program was developed in accordance with the European Standard (ESA PSS-049).

Two-phase capillary loops are being extensively studied as heat collection and rejection systems for space applications as they appear to satisfy several requirements like low weight, low volume, temperature control under variable heat loads and/or heat sink, operation under on ground and micro gravity conditions, simplicity of mounting and heat transfer through tortuous paths. In 1998–2000 Alenia defined and Lavochkin Association developed the Deployable Radiator on the base of honeycomb panels, axial grooved heat pipes and Loop Heat Pipe. It was designed for on-ground testing.

Some aspects of development and modeling of LHPs with several Evaporators are discussed. Design description and test results obtained for LHPs with two evaporators (“Push-Pull” LHP) and three Evaporators (“Zmey Gorynych” LHP) are presented.

Two-phase capillary loops are being extensively studied as heat collection and rejection systems for space applications as they appear to satisfy several requirements like low weight, low volume, temperature control under variable heat loads and/or heat sink, operation on ground and 0-g, simple mounting and heat transfer through tortuous paths. A Deployable Radiator with Loop Heat Pipe (LHP) with a heat transport capability of 1500 W has been defined and conceived by Alenia, and developed by Lavochkin Association under Alenia contract. In this paper a detailed description of the Deployable Radiator (and of its 1000 W LHP precursor) is presented, with emphasis on the areas that required research activities to improve performances. First test results are presented and discussed.

Some aspects of development and modeling of LHPs with several Evaporators are discussed. Design description and test results obtained for LHPs with two evaporators (“Push-Pull” LHP) and three Evaporators (“Zmey Gorynych” LHP) are presented.

Two-phase heat-transfer capillary pumped loops (CPL) are a promising basis for development of a new generation of thermal regulation systems of space vehicles. It is assumed that such systems will have considerably better performance characteristics than traditional one-phase ones with mechanical pumping. Experimental CPLs of various modifications with a heat-transfer capacity up to 1 kW and heat-transfer length up to 5 m filled up with freon-11, ammonia and propylene as heat-transfer agents were designed. Capillary pumps which are used in CPLs let create a pressure up to 40 kPa. They are simultaneously effective evaporative heat exchangers. CPLs are well regulated by different methods which make it possible to provide stabilization of the temperature of the capillary pump active zone on changing both heat load and conditions of heat removal to the environment. The results of terrestrial and flight tests have shown efficiency and reliability of CPLs.